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Re: Results of compression test (what now?)

To: Der schwarze Buccaneer <js-allen@students.uiuc.edu>
Subject: Re: Results of compression test (what now?)
From: Robert Allen <boballen@sky.net>
Date: Sat, 15 Nov 1997 20:03:52 +0000
Der schwarze Buccaneer wrote:
> 
> Anyone know what these results mean:
> 
>         Cylinder        Compression     With Oil In Chamber
>           1               110 lbf          120
>           2               116              125
>           3             >> 26 <<        >> 26 <<
>           4               108              120
> 
>         Now, my book says 130 is the normal value.  I assume this means
> that 1, 2, and 4 probably have bad rings, but how bad are they?

Did you have the throttle held open and a dowel under the dampers when
you ran your test? Compression test needs unrestricted intake. In any
case, the rings are a little tired in 1, 2 and 4. But if the engine was
cold its nothing to worry about.

At best, 130 is a low compression engine.

As the before/after (with oil) in #3 is the same, I'd suspect
burnt/broken valve. Can you run a little air pressure in #3 (leak down
test) Then you listen in the exhaust, intake, oil sump, and radiator to
figure bad exhaust valve, bad intake valve, bad rings/piston, or bad
head/head gasket respectively.

Or just yank the head and take a look. You're not far from doing that
anyway.

-- 
Bob Allen, Kansas City, '69CGT, '75TR6, '61Elva(?)
"The biggest thing that happened to the six-cylinder engine in 20 years
was the seven main-bearing crank" -- John Z. DeLorean, Car Life, 1966

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